Cooling of exhaust valves of internal-combustion engines



May 22, 1928. 1,670,965

S. D. HERON COOLING OF EXHAUST VALVES OF INTERNAL COMBUSTION ENGINES Filed June 9, 1923' attozmq Patented May 22, 1928. i

" UNITED STATES} an: n. nnnon, or nav'ron, onm.

COOLING OF EXHAUST VALVES OF INTERNAL-COMBUSTICN ENGINES.

Appllcationflled J'une 19 23. Serial No. 644,480.

invention relates in general to engine valves and is especially applicable for cooling the exhaust valves tion engines. 5. I am aware that it is not new in the art to provide such a valve with a hollow valve stem and to partially fill the hollow portion of the stem with some liquid for the purpose of cooling the valve. I am aware that the use nternal combus- W of a very small quantity of mercury or water for such a cooling liquid has been proposed, the coolingbeing accomplished by the b011- ing of the fluid in the lower part of the valve and thesubsequent'condensation at the upper 35 part of the valve stem. Mercury and water are, however, open to the objection that they volatilize below the working temperature of the valve and thus develop a vapor pressure within the valve which is difficult to hold and loss of the cooling medium thus fre-' Furthermore, the efli'ectlvequently results.

'ness or such a cooling medium is mat rally altered by the position or attitude f the valve. When such a cooling medium is to be used it is essential that the attitude of the valve bein vertical, or nearly so, and

\ that thevalve head be lower than the valve stem.

It is the object of my invention to obviate the dificulties above enumerated b supplying such a valve with a cooling me ium with the four following most important characteristics: first, it shall have a fusing pomt lower than the average working temperature of the valve; second, it shall have a vapor izing or decomposing temperature greatly in excess of the norma working temperature of the valve; third, it shall have the property "of wetting the hot surface of the interior of the valve and neither assume the spheroidal form as does water on hot iron or behave as does heated, mercury in a closed container;

and fourth, a sufiicient quantity of the med ium must be used so that the interior of the valve will be filled with a mixture of liquid gaseous material in which the volume and of the liquid is predominating.

It is thus the object of. my invention to provide a cooling medium in which the heat transfer is obtained by the use of a nonvolatile liquid which is maintained in a. violent state of turbance by the motion of the valve and which acts as a heat carrier by virtue of this turbance. It is essential that 55 this substance have the property of wetting be inserted in either end the valve-material to be efiicient' in the transfer of heatfrom the hot surfaces to the comparatively cooler surfaces of the valve. The

benefits of this system over the priorart is that the heat transfer is not afiected by the position or attitude of the valve, and further that the difficulty of keeping high.

pressure vapors in the valve stem 1s obviated.

In order that those skilled in the art may more readily ractice the invention which I have made, I ave described the same in the accompanying specifications and illustrated the same in the accompanying drawings in which I Fig. 1 is a central vertical section of a valve showing means for inserting a cooling medium into 1ts hollow valve stem.

Fig. 2 is a modification showing a closed valve.

Fig. 3 is a modification of Fig. 1 showing cooling fins in the valve stem, and;

Fig. 4 is a modificationshowing the cooling medium in the stem only.

Referring more particularly to the draw- 8 ings and reference being had first to Fig. 1, q it will be seen that I disclose a valve 1 having a hollow stem 2. The valve nearits uper end may be interiorly screw threaded and adapted to receive plug 4 or a plug may of the valve in any desirable manner. The plug 4: is provided with the usual valve tappet bearin surface 3 and when inserted, may be fixe in any manner (not shown) against rotation relative to the valve stem.' In Figure 2 is shown a closed valve which may be filled with the cooling mediumthrough an openin' at the bottom or side of the valve, the coofing medium being supplied, in the valve head as well as in the stem. In Figure 3is shown a modification in which cooling fins 6 are provided on the stem of the valve. In Fig. 4 is shown a valve in which the cooling medium is provided only in the stemof the valve and in which the plug number 7 is adapted to be driven into the stem with a mallet or arbor ress. In this modification the level of the iquid when the valve is at normal air temperature is indicated at 8, and numeral 9 indicates the level of the liqluid at the normal working temperature. propose to fill the hollow portion of the stem with. a considerable quanity of the cooling medium 5 leaving a sufiicient degree of 1 shall have the three following characteristics:

1. A fusing point lower than the working temperature of the valve.

2. A vaporizing or decomposin temperature greatly in excess of the wor ing temerature of the valve.

adapted to wet the surface of-the hot metal oft evalve. A

Such substances as potassium nitrate, sodium nitrate or lithium nitrate or any mixture thereof, or of metallic potassium, lithium or sodium, or of metallic potassium, lithium or sodium, and their salts, or of any combination of the alkaline metals and their salts, have been found to satisfy the above conditions. c

I have found that a mixture of 55% a potassium nitrate and 45% sodium nitrate 1se rceptionally well suited as a cooling medium asit has a melting temperature of about425 F. which is well below the working temperature of theportions of the valve in contact with the cooling medium. The valve is filled with the liquid salt mixture at about 750 F. An ejector rod is then inserted temporarily in order to-force out. a suitably quantity of the liquid so that when the ejector rod is removed the level of the liquid (see Fig. 4) will be as shown in the dotted lines designated 9. The plug 7 is then driven home with. a mallet or arbor press. After the valve cools the liquid level w1ll be at 8. The valve is filled at 750 F.

as this is ap roximately the working temperature of t e valve, and there will therefore be no material internal pressure on the valve stem when the same is operating.

The length of the internal chamber in Fig. 4 which is not filled with the liquid is from 1 to 2 times the distance travelled by the valvein its reciprocating motion, so that a proper turbulent action will be produced in the liquid.

From the above' description it will be readily seen that I will have avoided to a large extent the" formation of vapor pressure lnside the valve and that I will have rovided for a cooling which shall be entirely due to the turbulent circulation of a cooling liquid formed, this circulation being produced by temperature gradients in the coolingmedium and by the motion of the valve rather than by bolling and subsequent condensation as has heretofore been the practice.

I claim:

1. A hollow valve containing a cooling medium withinthe same under substantially normal atmospheric pressure at the average working temperature of the valve in suflicient quantity to provide violent turbulence under operating conditions.

2. A hollow metal part adapted to operate back and forth rapidly at a high normal temperature, having a cooling medium therein under substantially atmospheric pressure at the normal working temperature of the part, and having a lower fusing point and higher vaporizing point than the operating temperature of the part, said. medium only partially filling the space within said part 3. It shall have the characteristic of being ing a cooling medium therein containing a nitrate of an alkalimetal under substantially atmospheric pressure at the normal working temperature of the part, and having a lower fusing point and higher vaporizing point than the operating temperature of the part, said medium only partially filling the space within said part to permit "a turbulence of the medium, said medium havingthe property of wetting the interior of the part under operating conditions.

4. A hollow metal part adapted to operate back and forth rapidly at a temperature of several hundred degrees Fahrenheit, having a cooling medium therein which-will not attack the part under operating conditions, said medium being under substantially atmos pheric pressure at the normal working temperature of the part, andhaving a lower fusing point and higher vaporizing point than medium only partially filling the space within said part to permit a turbulence of the medium, said medium having the property of wetting the interior of the part \under operating conditions. i

5. A metal engine part adaptedto operate backfland forth rapidly at a normal working temperature, of several hundred degrees F., having a closed chamber partly filled with a cooling medium which has a specific gravity less than iron and remains liquid at. the normal workin temperature of the part to provide for eat transfer by the turbulent circulation of themedium in a liquid state.

6. A metal part adapted to operate back and forth rapidly at a normal working tem perature of several hundred degrees F., having a closed chamber therein containing a cooling medium which fills a large part of the chamber without completely filling it, the medium having a specific gravity less than mercury and beingliquid at the normal working temperature of the part to provide for heat transfer by the turbulent circulation of the medium in a liquid state,

' 1,avo,eea

I the medium having the property of wetting the interior of the part without chemically attacking it in an objectionable degree.

containing a cooling medium which fills a' large part of the chamber without completely filling to provide a turbulent action, the medium comprising a substance of the alkali metal group liaving a specific gravity less 1 than iron and remaining liquid at the normal working temperature of the part to provide for heat transfer by the turbulent circulation ofithe medium in a liquid state.

8. A metal valve adapted to operate back and forth rapidly at a workin temperature of several hundred degrees having a closed chamber therein containin a cooling medium which fills a large part 0% the chamber with'outfcompletely fillin it to provide a turbulent action of-the me 'um under operating conditions, the medium comprising a mixture of alkali metal salts, and being a liquid at the normal working temperture of the valve to provide for heat transfer by the violent circulation of the medium in a liquid state. a

r 9. An exhaust valve for internal combustion engines adapted to operate back and forth rapidly at a hi h' normal working temperature, havin a c osed chamber therein containin a coo ing medium only partly filling the chamber to provide a turbulent action of the medium under operating conditions, the medium comprising an alkali metal substance and having .a higher decomposing or vaporizin temperature than 750 F., having a speci c gravity considerablyless than mercury and being liquid at the normal working temperature of the valve to provide for heat transfer by the turbulent circulation of'the medium.

10. An engine valve adapted to operate back' and forth rapidly while having the valve head subjected to temperatures of a high order, said valve havin a closed cham-- ber therein containing a coo in medium the vaporization temperature of w ich is above the usual operating temperature of the valve parts which fills a large part of the chamber withoutcompletely fillin it to provide for heat transfer from the va ve head to the cooler. valve stem by transfer b the turbulent circulation o-f'the cooling me ium in a liquid state. i

In testimony whereof I afiix miIsi ature. 

